THE PROGNOSTIC VALUE OF ONCOGENIC ANTIGEN-519 (OA-519) EXPRESSION AND PROLIFERATIVE ACTIVITY DETECTIVE BY ANTIBODY MIB-1 IN NODE-NEGATIVE BREAST-CANCER

The prognostic value of oncogenic antigen 519 (OA-519) expression and tumour proliferative activity was evaluated in a retrospective series of 118 patients with low-risk breast cancer. Low risk was defined as negative axillary nodes, tumour diameter less than or equal to 50 mm, and no histological evidence of invasion of skin or deep fascia (= T(1)N(0)M(0) and T(2)N(0)M(0)). The median follow-up time was 104 months (range 5-143 months). Immunohistochemical analysis of OA-519 expression was performed on formalin-fixed, paraffin-embedded tissue. The proliferative activity was estimated using a Ki-67 equivalent monoclonal antibody (MIB-1), which is applicable on formalin-fixed, paraffin-embedded tissue after microwave pretreatment. OA-519 was expressed in about one-third of the tumours and the percentage of proliferating cells (the MIB-1 index) ranged between 1 and 72 per cent (median 17 per cent). Using multivariate Cox analysis, both the MIB-1 index and OA-519 expression were of independent prognostic value (2p less than or equal to 0 . 01), and the combined immunohistological approach may therefore be useful in selecting patients with node-negative breast cancer who might benefit from adjuvant therapy.